1. Field of the Invention
The present invention relates generally to safety systems and arrangements and in particular to a fall protection arrangement, such as a controlled descent device, including self-retracting lanyards and the like, which may be used in connection with a harness to protect the wearer from a sudden, accelerated fall arrest event.
2. Description of the Related Art
As is known in the art of safety systems and processes, a lanyard, such as a self-retracting lanyard (SRL), are used for fall protection in both industrial environments, as well as in connection with recreational activities. Self-retracting lanyards have numerous industrial end uses, including, but not limited to, construction, manufacturing, hazardous materials/remediation, asbestos abatement, spray painting, sand blasting, welding, mining, numerous oil and gas industry applications, electric and utility, nuclear energy, paper and pulp, sanding, grinding, stage rigging, roofing, scaffolding, telecommunications, automotive repair and assembly, warehousing, and railroading. Some tend to be more end-use specific than others, like the building/construction system of U.S. Pat. No. 6,695,095 or the roof anchoring system of U.S. Pat. No. 5,730,407. One representative SRL is shown and described in U.S. Publication No. 2007/0215410, the disclosure of which is incorporated by reference herein.
Further, there exist numerous SRLs, or lifelines, in the field of fall protection and related safety equipment. They can and should be worn by an individual when there is any risk of falling. Such SRLs generally consist of a housing that includes a rotatable drum or hub around which a line, typically made of webbing, cable, rope, and/or synthetic material is wound. The hub rotates in a first direction to unwind (or “pay out”) the line from its housing when a certain level of tension is purposefully applied. When that degree of tension is reduced or released, the hub can slowly rotate in a reverse direction causing the line to retract or rewind about itself in a desired manner. Certain housings further include a braking mechanism or assembly for resisting hub rotation when an inelastic line (e.g., a steel cable) unwinds too rapidly, i.e., faster than its predetermined maximum velocity for normal pay out. A sudden line pay out is an indication that the lanyard wearer/user has experienced a fall that needs to be stopped or arrested.
Should an unintentional, accidental fall commence, an engagement and braking arrangement in the housing of the SRL engages, which prevents the SRL wearer from falling too far. In addition, SRLs typically connect at one end to an anchorage point, often on the support structure at or near where a user is performing certain assigned tasks. The line from the SRL housing is clamped (or otherwise attached) to a harness worn by the worker. One representative harness is shown and described in U.S. Pat. No. 6,804,830, the disclosure of which is incorporated by reference herein. Other known models of SRLs include those disclosed in: U.S. Pat. Nos. 6,810,997; 5,186,289; 4,877,110; and U.S. Publication No. 2005/0051659.
Therefore, while many different models and arrangements of SRLs exist, one common problem that arises with the braking mechanism is the galling or uneven wear that occurs in connection with portions of the braking mechanism, such as the friction pads. This galling effect leads to variability in performance due to the variability in contact and pressure points between adjacent surfaces in the mechanism. Further, this increased variability may lead to product failure and reduced effectiveness in operation.
In addition, in the field of fall arrest devices, the maximum allowable stopping forces and distances are defined by known industry standards. The stopping force provided by a brake is inversely proportional to the stopping distance, i.e., the higher the force the shorter the distance, and vice versa. As a result, the force cannot exceed the maximum allowed by standards, and yet it must also be large enough so that the extension distance does not exceed the maximum also regulated by these standards. Accordingly, large force and extension variations (which result from galling and uneven wear) require designers to develop products with tight design limits to account for this variation. Therefore, a reduction in this variation allows for expanded design windows that are more easily achieved in the manufacturing process, which results in a product that is more robust and cost effective to manufacture.
Accordingly, there remains a need in the field for improved fall protection and arrest devices and systems that lead to enhanced safety characteristics and user protection in certain environments and situations.